Peak 1 loses retention over time, but peak 2 retention time remains stable on Atlantis Premier BEH C18 AX column - WKB260899

SYMPTOMS

• Peak 1 of interest loses retention time and starts to co-elute with peak 2, which remains stable with each injection (no loss of retention)
• Only the one peak is moving
• Changing the guard does not fix the problem
• Column used for undisclosed number of standard injections during method development
• Retention time shift for peak 1 occurs before 60 injections of sample

ENVIRONMENT

• HPLC
• Retention time shift
• Mixed-mode chemistry
• Column care and use
• Column cleaning 
• Column 186009412 (Atlantis C18 AX, 5 µm, 4.6x150 mm MPFIT)

CAUSE

Final formulation composition in the samples contains surfactant that builds up on columns and changes the surface chemistry. 

FIX or WORKAROUND

1. Clean the column. 
2. Flush the column with 60:40 methanol/water at 1 mL/min for 1 hour.
3. Follow with 80:20 acetonitrile/water at 1 mL/min for 50 minutes.

ADDITIONAL INFORMATION

For additional cleaning options, see the Atlantis Premier BEH C18 AX Columns Care and Use Manual.